Air flow control ler damper for air supply or exhausting systems



April 17, 1962 w. H. BARKER ETAL AIR FLow CONTROLLER DAMPER FOR AIR SUPPLY OR EXHAUSTING SYSTEMS Filed Nov. 8, 1957 2 Sheets-Sheet 1 ATTORNEY April 17, 1962 w. H. BARKER ETAL 3,029,722

AIR FLOW CONTROLLER DAMPER FOR AIR SUPPLY OR EXHAUSTING SYSTEMS 2 Sheets-Sheet 2 Filed NOV. 8, 195'? 34%??? IV L mmn e fg RHBARKER wow A TTORNE Y l t l l l United States Patent C) 3,029,722 AIR FLOW CGOLLER DER FOR SUPPLY R EXHAUSTHNG SYSTEMS William Harry Barker, Silverwood Camden Park Road, Chislehurst, and Derek Richard Barker, St. hristopher Bickley Park Road, both of Bromley, England Filed Nov. 8, 1957, Ser. No. 695,428 1 Claim. (Cl. 98-40) The present invention relates to an air flow controller or damper (referred to hereinafter as a damper) for air supply and exhausting systems and has for its object to provide an improved damper comprising a plurality of louvres or vanes which are constructed and arranged in such a manner that air passing through the damper is caused to leave it in streams which are parallel, or substantially parallel, with the axis of a duct or the equivalent in which the damper is mounted.

The invention is more particularly, although not exclusively, concerned with air supply .or exhausting systems comprising a main duct through which air is caused to pass and which is discharged through one or more lateral ducts or openings. The disadvantage experienced with such arrangements is that the air is not discharged evenly through said lateral ducts or openings because the air sweeps over the first part of the lateral duct with the result that a minimum amount of air is deflected through said first part and a maximum amount of air through the second or remaining part so that not only does the air pass through the lateral duct in non-parallel streams but an air vortex sometimes occurs in the first encountered part of the lateral duct through which the minimum of air passes.

According to the present invention there is provided an air flow damper for air supply or exhausting systems comprising a plurality of spaced apart V form louvres, each comprising a pair of blades arranged to form a V in cross section, said louvres being supported so that the apices of the Vs are parallel and all point in the same direction and are contained in the same plane, and means for splaying apart each pair of blades to increase the angle therebetween to vary the size of the gap between the outer free edges of opposed blades of adjacent pairs of blades, said means acting on the louvres in such a manner that the said pairs of blades can be adjusted simultaneously and splayed apart by progressively corelated different amounts from one end of the damper to the other so that the size of the gaps between the opposed blades of adjacent louvres increases progressively.

Such an arrangement results in the gaps between the louvres first encountered by the air stream being larger than those which are encountered by the air stream afterwards so that thereis little impedence or resistance to the air when it first encounters the damper and progressively 'increased resistance as the .air passes across the damper so that an evening out or balancing of the air is effected which results in the air being discharged from the damper in streams parallel with the axis of the duct in which the damper is fitted and so that the volume is even over the entire area of the damper.

In cross section the louvres can be said to be represented by a line of Vs the spaces between opposed free edges of which increase progressively so that a minimum mum size gap is provided between the opposed free edges of two adjacent louvres at one end or side of the damper and the maximum size gap between the opposed free edges of two adjacent louvres at the other end or side of the damper.

To enable the invention to be clearly understood a preferred embodiment thereof will now be described by way "ice of example with reference to the accompanying drawings, wherein:

FlGURE l is an elevation with parts broken away to expose others.

FIGURE 2 is a plan view partly in section FlGURE 3 is an end view partly in section, and

FEGURE 4 is a diagrammatic View similar to FIG- URE 2 but drawn to a smaller scale showing how the size of the gaps between the louvres increases and decreases progressively.

Referring to the drawings, the louvres 1 are mounted in an oblong or square duct or casing 2 but it is to be appreciated that they could be adapted for mounting in a circular duct.

The apices of the said louvres 1 are mounted uni-directionally in the same plane in equally spaced apart parallel relation so as to extend across two opposite walls 3 of the duct 2, or the walls of a casing for mounting in the duct, and each louvre 1 comprising a pair of separate blades 4 which are arranged in V formation and adapted to hinge about their edges forming the apex of the V. The blades 4 of each V section louvre 1 are adapted to be urged or splayed apart against the influence of yieldable means, e.g. spring means, which tends to move said limbs towards one another. I

The louvres l forwardly of their apices and at their ends, bear on fulcrum members which maybe in the form of pins 5 provided on the opposite side walls 3 of the casing, so that major and minor portions of the said blades 4 of the V louvres are located forwardly and rearwardly respectively of the axes of said pins 5.

Conveniently, the minor portions 4b of the blades 4 have their rear free edges dadjacent the apices of the louvres semi-circularly shaped to engage a locating rod '7 which extends along the apex of the louvre, the ends of said rod engaging respectively in slots 8 in opposite sides of the casing.

The louvres 1 are supported loosely on said fulcrum pins 5 so it will be appreciated that any pressure brought to bear on the apices of the louvres will result in their limbs 4 being splayed apart about the fulcrum pins as the louvres are displaced very slightly in their own plane.

Each of the blades 4 (as clearly shown in FlGURES 2 and 4) is shaped longitudinally in cross section in the form of a shallow or obtuse V with the limbs of the V of unequal length, the minor limb constituting an abutment face which bears on the pin 5 and is moved angularly slightly by variation of the pressure applied to the apex of the louvre to bring about the desired corresponding deflection of the associated major limb 4c thereof. The outer free edge 4A of each blade 4 is disposed downstream of the air flow through the damper while the rear edge 6 of each blade is mounted upstream with respect to the louvre.

The splaying apart of the blades 4 of the louvres is affected against theinfluence of 6 section springs 9 provided one at each end of each louvre 1 and at the centre and which nip the blades together where they are shaped to engage said thin rod 7 extending along the apex of the louvre.

One convenient means for applying pressure to the apices of the louvres 1 comprises a four-sided frame which fits inside the casing 2 with two opposite parallel limbs 10 (termed pressure limbs) bridging and engaging the apices of the louvres l at the ends thereof. The remaining two parallel limbs 11 of the frame (which will be termed setting) limbs, and which are in parallelism with the apices of the louvres 1, are each supported so that they can be displaced to swing the pressure limbs 10 of the frametowards or away from the apices of the louvres 1.

By maintaining one of the setting limbs 11 stationary and adjusting the other setting limb 11 it will be appreciated that the frame is swung bodily about the stationary setting limb and that the maximum swinging movement of the pressure limbs 16 takes place at the ends remote from the stationary setting limb 11 and as the arc swung through by various points along at the length of each pressure limb increases from one end to the other it will be seen that the louvres 1 are depressed diflferent amounts simultaneously and that the blades of the louvres are opened apart different amounts (see FIGURE 4) so that the gaps between the louvres 1 at their outlets, that is the gaps 1 2. defined by the free edges of the blades 4 of adjacent louvres -1, increases progressively.

Each setting limb 11 of the frame is connected eg by welding, to a short bar 13 which is parallel to the adjacent side wall of the casing 2 and the lower end 14 of this bar 13 is bent at right angles and formed with a screw-threaded hole for receiving a screw 15. This screw 15 passes freely through a hole in a lug 16 bent out of'the material of the casing wall the screw having a nut 17 welded to its free end. The screw 15 is held against axial displacement ,by the nut 17 and the louvres closing spring action which is transmitted to the frame 10-11. The arrangement is such that when the screw 15 is turned, by applying a tool to said nut 17, the said short bar 13 is moved endways one way or the other depending upon the direction of turning of the screw 15, so that the bar 16 either pulls on the setting limb 11 and swings it to urge the pressure limbs 10 of the frame against the apices of the louvres 1 or, allows the pressure to relax and the louvres 1' to close slightly under the influence of their springs, the closing of the louvres '1 swinging the pressurelirnbs 10 in the opposite direction.

The onter'blades 4 of the two end louvres are formed with clearance notches which may be in the form of V- cut-out 4A (FIGURE 3) so that these parts of the blades do not foul the setting screws 15. t

It will be appreciated that either of the setting limbs 11 can be actuated to swing the pressure limbs 16 one way or the other so that gaps 12 between the free edges of adjacent louvres 1 can progressively increase from one side of the casing to the other, or vice versa, and that intermediate sizes of gaps can be obtained by manipulating both the short bars 13 by turning their screws 15.

In this manner the quantity or volume of air passing through the unit may be varied very accurately by a progressive adjustment from a maximum to a minimum amount, or alternatively, completely shut ofi.

Instead of welding the short bars 13 to the setting limbs, the upper ends of the bars 13 may be bent at right angles over the top edges of the setting limbs 1-1.

When the pressure limbs 10 are urged against the apices of the louvres 1 the blades 4 are splayed apart by reason of the fact that they are urged against said fulcrum pins 5 rearwardly of their apices, this splaying apart taking place against the resistance of the C-springs 9 which close the blades 4 together when the pressure is relaxed.

'It should be explained that only a slight adjustment of the screws 15 is necessary to set the blades and that the swinging movement of the pressure limbs 10 is hardly perceptible. I

The damper is adjusted when-it is first installed and once set to give the best results need not be readjusted unless circumstances alter.

What we claim is:

An air flow damper for air supply or exhausting systems comprising, a casing, a plurality of spaced apart louvres disposed in said casing and each comprising a pair of blades arranged to form a V in cross-section, rear edges on said blades pointing upstream of the air flow through the damper and forming apices of said louvres, said blades each having an outer free edge pointing downstream of the air flow through the damper and the outer free edges of the opposed blades of adjacent louvres cooperating to define air flow gaps, locating rods extending along the apices of said V-shaped louvres and mounted in opposite ends of said casing for horizontal reciprocating movement, said casing supporting said rods and the apices of said louvres in parallel relationship, each of said pair of blades constituting said louvres comprising major and minor blade portions, said minor blade portions of each louvre disposed adjacent said locating rod and shaped in cross-section in the form of an obtuse V and said major blade portions disposed adjacent said outer free edges and shaped in the form of an acute V, each of said rear edges of said pair of blades of each louver shaped to engage one of said locating rods, spring means means retaining said rear edgesin engagement with said rods to bias each pair of cooperating blades forming a louvre towards each other, fulcrum members disposed between said minor portions of each pair of cooperating blades defining said louvres, pressure limbs 'mounted in a plane at right angles to and in contact with the apices of said louvres, a pair of setting limbs supporting said pressure limbs in said casing and urging said pressure limbs against the apices of said louvres to bias said minor portions of said obtuse V sections of the louvres downstream of the air flow and against the said fulcrum members to splay apart said major blade por- 1 References Cited in the file of this patent UNITED STATES PATENTS 1,931,263 McNight Oct. 17, 1933 2,149,976 McNight Mar. 7, 1939 2,224,312

O Day Dec. 10, 1940 

